source: trunk/sys/libz/deflate.c @ 1

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1/* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2005 Jean-loup Gailly.
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6/*
7 *  ALGORITHM
8 *
9 *      The "deflation" process depends on being able to identify portions
10 *      of the input text which are identical to earlier input (within a
11 *      sliding window trailing behind the input currently being processed).
12 *
13 *      The most straightforward technique turns out to be the fastest for
14 *      most input files: try all possible matches and select the longest.
15 *      The key feature of this algorithm is that insertions into the string
16 *      dictionary are very simple and thus fast, and deletions are avoided
17 *      completely. Insertions are performed at each input character, whereas
18 *      string matches are performed only when the previous match ends. So it
19 *      is preferable to spend more time in matches to allow very fast string
20 *      insertions and avoid deletions. The matching algorithm for small
21 *      strings is inspired from that of Rabin & Karp. A brute force approach
22 *      is used to find longer strings when a small match has been found.
23 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24 *      (by Leonid Broukhis).
25 *         A previous version of this file used a more sophisticated algorithm
26 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
27 *      time, but has a larger average cost, uses more memory and is patented.
28 *      However the F&G algorithm may be faster for some highly redundant
29 *      files if the parameter max_chain_length (described below) is too large.
30 *
31 *  ACKNOWLEDGEMENTS
32 *
33 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34 *      I found it in 'freeze' written by Leonid Broukhis.
35 *      Thanks to many people for bug reports and testing.
36 *
37 *  REFERENCES
38 *
39 *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40 *      Available in http://www.ietf.org/rfc/rfc1951.txt
41 *
42 *      A description of the Rabin and Karp algorithm is given in the book
43 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44 *
45 *      Fiala,E.R., and Greene,D.H.
46 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47 *
48 */
49
50/* @(#) $Id$ */
51
52#include "deflate.h"
53
54const char deflate_copyright[] =
55   " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly ";
56/*
57  If you use the zlib library in a product, an acknowledgment is welcome
58  in the documentation of your product. If for some reason you cannot
59  include such an acknowledgment, I would appreciate that you keep this
60  copyright string in the executable of your product.
61 */
62
63/* ===========================================================================
64 *  Function prototypes.
65 */
66typedef enum {
67    need_more,      /* block not completed, need more input or more output */
68    block_done,     /* block flush performed */
69    finish_started, /* finish started, need only more output at next deflate */
70    finish_done     /* finish done, accept no more input or output */
71} block_state;
72
73typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74/* Compression function. Returns the block state after the call. */
75
76local void fill_window    OF((deflate_state *s));
77local block_state deflate_stored OF((deflate_state *s, int flush));
78local block_state deflate_fast   OF((deflate_state *s, int flush));
79#ifndef FASTEST
80local block_state deflate_slow   OF((deflate_state *s, int flush));
81#endif
82local void lm_init        OF((deflate_state *s));
83local void putShortMSB    OF((deflate_state *s, uInt b));
84local void flush_pending  OF((z_streamp strm));
85local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
86#ifndef FASTEST
87#ifdef ASMV
88      void match_init OF((void)); /* asm code initialization */
89      uInt longest_match  OF((deflate_state *s, IPos cur_match));
90#else
91local uInt longest_match  OF((deflate_state *s, IPos cur_match));
92#endif
93#endif
94local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
95
96#ifdef DEBUG
97local  void check_match OF((deflate_state *s, IPos start, IPos match,
98                            int length));
99#endif
100
101/* ===========================================================================
102 * Local data
103 */
104
105#define NIL 0
106/* Tail of hash chains */
107
108#ifndef TOO_FAR
109#  define TOO_FAR 4096
110#endif
111/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
112
113#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
114/* Minimum amount of lookahead, except at the end of the input file.
115 * See deflate.c for comments about the MIN_MATCH+1.
116 */
117
118/* Values for max_lazy_match, good_match and max_chain_length, depending on
119 * the desired pack level (0..9). The values given below have been tuned to
120 * exclude worst case performance for pathological files. Better values may be
121 * found for specific files.
122 */
123typedef struct config_s {
124   ush good_length; /* reduce lazy search above this match length */
125   ush max_lazy;    /* do not perform lazy search above this match length */
126   ush nice_length; /* quit search above this match length */
127   ush max_chain;
128   compress_func func;
129} config;
130
131#ifdef FASTEST
132local const config configuration_table[2] = {
133/*      good lazy nice chain */
134/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
135/* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
136#else
137local const config configuration_table[10] = {
138/*      good lazy nice chain */
139/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
140/* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
141/* 2 */ {4,    5, 16,    8, deflate_fast},
142/* 3 */ {4,    6, 32,   32, deflate_fast},
143
144/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
145/* 5 */ {8,   16, 32,   32, deflate_slow},
146/* 6 */ {8,   16, 128, 128, deflate_slow},
147/* 7 */ {8,   32, 128, 256, deflate_slow},
148/* 8 */ {32, 128, 258, 1024, deflate_slow},
149/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
150#endif
151
152/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
153 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
154 * meaning.
155 */
156
157#define EQUAL 0
158/* result of memcmp for equal strings */
159
160#ifndef NO_DUMMY_DECL
161struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
162#endif
163
164/* ===========================================================================
165 * Update a hash value with the given input byte
166 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
167 *    input characters, so that a running hash key can be computed from the
168 *    previous key instead of complete recalculation each time.
169 */
170#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
171
172
173/* ===========================================================================
174 * Insert string str in the dictionary and set match_head to the previous head
175 * of the hash chain (the most recent string with same hash key). Return
176 * the previous length of the hash chain.
177 * If this file is compiled with -DFASTEST, the compression level is forced
178 * to 1, and no hash chains are maintained.
179 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
180 *    input characters and the first MIN_MATCH bytes of str are valid
181 *    (except for the last MIN_MATCH-1 bytes of the input file).
182 */
183#ifdef FASTEST
184#define INSERT_STRING(s, str, match_head) \
185   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
186    match_head = s->head[s->ins_h], \
187    s->head[s->ins_h] = (Pos)(str))
188#else
189#define INSERT_STRING(s, str, match_head) \
190   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
191    match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
192    s->head[s->ins_h] = (Pos)(str))
193#endif
194
195/* ===========================================================================
196 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
197 * prev[] will be initialized on the fly.
198 */
199#define CLEAR_HASH(s) \
200    s->head[s->hash_size-1] = NIL; \
201    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
202
203/* ========================================================================= */
204int ZEXPORT deflateInit_(strm, level, version, stream_size)
205    z_streamp strm;
206    int level;
207    const char *version;
208    int stream_size;
209{
210    return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
211                         Z_DEFAULT_STRATEGY, version, stream_size);
212    /* To do: ignore strm->next_in if we use it as window */
213}
214
215/* ========================================================================= */
216int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
217                  version, stream_size)
218    z_streamp strm;
219    int  level;
220    int  method;
221    int  windowBits;
222    int  memLevel;
223    int  strategy;
224    const char *version;
225    int stream_size;
226{
227    deflate_state *s;
228    int wrap = 1;
229    static const char my_version[] = ZLIB_VERSION;
230
231    ushf *overlay;
232    /* We overlay pending_buf and d_buf+l_buf. This works since the average
233     * output size for (length,distance) codes is <= 24 bits.
234     */
235
236    if (version == Z_NULL || version[0] != my_version[0] ||
237        stream_size != sizeof(z_stream)) {
238        return Z_VERSION_ERROR;
239    }
240    if (strm == Z_NULL) return Z_STREAM_ERROR;
241
242    strm->msg = Z_NULL;
243    if (strm->zalloc == (alloc_func)0) {
244        strm->zalloc = zcalloc;
245        strm->opaque = (voidpf)0;
246    }
247    if (strm->zfree == (free_func)0) strm->zfree = zcfree;
248
249#ifdef FASTEST
250    if (level != 0) level = 1;
251#else
252    if (level == Z_DEFAULT_COMPRESSION) level = 6;
253#endif
254
255    if (windowBits < 0) { /* suppress zlib wrapper */
256        wrap = 0;
257        windowBits = -windowBits;
258    }
259#ifdef GZIP
260    else if (windowBits > 15) {
261        wrap = 2;       /* write gzip wrapper instead */
262        windowBits -= 16;
263    }
264#endif
265    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
266        windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
267        strategy < 0 || strategy > Z_FIXED) {
268        return Z_STREAM_ERROR;
269    }
270    if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
271    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
272    if (s == Z_NULL) return Z_MEM_ERROR;
273    strm->state = (struct internal_state FAR *)s;
274    s->strm = strm;
275
276    s->wrap = wrap;
277    s->gzhead = Z_NULL;
278    s->w_bits = windowBits;
279    s->w_size = 1 << s->w_bits;
280    s->w_mask = s->w_size - 1;
281
282    s->hash_bits = memLevel + 7;
283    s->hash_size = 1 << s->hash_bits;
284    s->hash_mask = s->hash_size - 1;
285    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
286
287    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
288    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
289    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
290
291    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
292
293    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
294    s->pending_buf = (uchf *) overlay;
295    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
296
297    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
298        s->pending_buf == Z_NULL) {
299        s->status = FINISH_STATE;
300        strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
301        deflateEnd (strm);
302        return Z_MEM_ERROR;
303    }
304    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
305    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
306
307    s->level = level;
308    s->strategy = strategy;
309    s->method = (Byte)method;
310
311    return deflateReset(strm);
312}
313
314/* ========================================================================= */
315int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
316    z_streamp strm;
317    const Bytef *dictionary;
318    uInt  dictLength;
319{
320    deflate_state *s;
321    uInt length = dictLength;
322    uInt n;
323    IPos hash_head = 0;
324
325    if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
326        strm->state->wrap == 2 ||
327        (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
328        return Z_STREAM_ERROR;
329
330    s = strm->state;
331    if (s->wrap)
332        strm->adler = adler32(strm->adler, dictionary, dictLength);
333
334    if (length < MIN_MATCH) return Z_OK;
335    if (length > MAX_DIST(s)) {
336        length = MAX_DIST(s);
337        dictionary += dictLength - length; /* use the tail of the dictionary */
338    }
339    zmemcpy(s->window, dictionary, length);
340    s->strstart = length;
341    s->block_start = (long)length;
342
343    /* Insert all strings in the hash table (except for the last two bytes).
344     * s->lookahead stays null, so s->ins_h will be recomputed at the next
345     * call of fill_window.
346     */
347    s->ins_h = s->window[0];
348    UPDATE_HASH(s, s->ins_h, s->window[1]);
349    for (n = 0; n <= length - MIN_MATCH; n++) {
350        INSERT_STRING(s, n, hash_head);
351    }
352    if (hash_head) hash_head = 0;  /* to make compiler happy */
353    return Z_OK;
354}
355
356/* ========================================================================= */
357int ZEXPORT deflateReset (strm)
358    z_streamp strm;
359{
360    deflate_state *s;
361
362    if (strm == Z_NULL || strm->state == Z_NULL ||
363        strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
364        return Z_STREAM_ERROR;
365    }
366
367    strm->total_in = strm->total_out = 0;
368    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
369    strm->data_type = Z_UNKNOWN;
370
371    s = (deflate_state *)strm->state;
372    s->pending = 0;
373    s->pending_out = s->pending_buf;
374
375    if (s->wrap < 0) {
376        s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
377    }
378    s->status = s->wrap ? INIT_STATE : BUSY_STATE;
379    strm->adler =
380#ifdef GZIP
381        s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
382#endif
383        adler32(0L, Z_NULL, 0);
384    s->last_flush = Z_NO_FLUSH;
385
386    _tr_init(s);
387    lm_init(s);
388
389    return Z_OK;
390}
391
392/* ========================================================================= */
393int ZEXPORT deflateSetHeader (strm, head)
394    z_streamp strm;
395    gz_headerp head;
396{
397    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
398    if (strm->state->wrap != 2) return Z_STREAM_ERROR;
399    strm->state->gzhead = head;
400    return Z_OK;
401}
402
403/* ========================================================================= */
404int ZEXPORT deflatePrime (strm, bits, value)
405    z_streamp strm;
406    int bits;
407    int value;
408{
409    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
410    strm->state->bi_valid = bits;
411    strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
412    return Z_OK;
413}
414
415/* ========================================================================= */
416int ZEXPORT deflateParams(strm, level, strategy)
417    z_streamp strm;
418    int level;
419    int strategy;
420{
421    deflate_state *s;
422    compress_func func;
423    int err = Z_OK;
424
425    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
426    s = strm->state;
427
428#ifdef FASTEST
429    if (level != 0) level = 1;
430#else
431    if (level == Z_DEFAULT_COMPRESSION) level = 6;
432#endif
433    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
434        return Z_STREAM_ERROR;
435    }
436    func = configuration_table[s->level].func;
437
438    if (func != configuration_table[level].func && strm->total_in != 0) {
439        /* Flush the last buffer: */
440        err = deflate(strm, Z_PARTIAL_FLUSH);
441    }
442    if (s->level != level) {
443        s->level = level;
444        s->max_lazy_match   = configuration_table[level].max_lazy;
445        s->good_match       = configuration_table[level].good_length;
446        s->nice_match       = configuration_table[level].nice_length;
447        s->max_chain_length = configuration_table[level].max_chain;
448    }
449    s->strategy = strategy;
450    return err;
451}
452
453/* ========================================================================= */
454int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
455    z_streamp strm;
456    int good_length;
457    int max_lazy;
458    int nice_length;
459    int max_chain;
460{
461    deflate_state *s;
462
463    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
464    s = strm->state;
465    s->good_match = good_length;
466    s->max_lazy_match = max_lazy;
467    s->nice_match = nice_length;
468    s->max_chain_length = max_chain;
469    return Z_OK;
470}
471
472/* =========================================================================
473 * For the default windowBits of 15 and memLevel of 8, this function returns
474 * a close to exact, as well as small, upper bound on the compressed size.
475 * They are coded as constants here for a reason--if the #define's are
476 * changed, then this function needs to be changed as well.  The return
477 * value for 15 and 8 only works for those exact settings.
478 *
479 * For any setting other than those defaults for windowBits and memLevel,
480 * the value returned is a conservative worst case for the maximum expansion
481 * resulting from using fixed blocks instead of stored blocks, which deflate
482 * can emit on compressed data for some combinations of the parameters.
483 *
484 * This function could be more sophisticated to provide closer upper bounds
485 * for every combination of windowBits and memLevel, as well as wrap.
486 * But even the conservative upper bound of about 14% expansion does not
487 * seem onerous for output buffer allocation.
488 */
489uLong ZEXPORT deflateBound(strm, sourceLen)
490    z_streamp strm;
491    uLong sourceLen;
492{
493    deflate_state *s;
494    uLong destLen;
495
496    /* conservative upper bound */
497    destLen = sourceLen +
498              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
499
500    /* if can't get parameters, return conservative bound */
501    if (strm == Z_NULL || strm->state == Z_NULL)
502        return destLen;
503
504    /* if not default parameters, return conservative bound */
505    s = strm->state;
506    if (s->w_bits != 15 || s->hash_bits != 8 + 7)
507        return destLen;
508
509    /* default settings: return tight bound for that case */
510    return compressBound(sourceLen);
511}
512
513/* =========================================================================
514 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
515 * IN assertion: the stream state is correct and there is enough room in
516 * pending_buf.
517 */
518local void putShortMSB (s, b)
519    deflate_state *s;
520    uInt b;
521{
522    put_byte(s, (Byte)(b >> 8));
523    put_byte(s, (Byte)(b & 0xff));
524}
525
526/* =========================================================================
527 * Flush as much pending output as possible. All deflate() output goes
528 * through this function so some applications may wish to modify it
529 * to avoid allocating a large strm->next_out buffer and copying into it.
530 * (See also read_buf()).
531 */
532local void flush_pending(strm)
533    z_streamp strm;
534{
535    unsigned len = strm->state->pending;
536
537    if (len > strm->avail_out) len = strm->avail_out;
538    if (len == 0) return;
539
540    zmemcpy(strm->next_out, strm->state->pending_out, len);
541    strm->next_out  += len;
542    strm->state->pending_out  += len;
543    strm->total_out += len;
544    strm->avail_out  -= len;
545    strm->state->pending -= len;
546    if (strm->state->pending == 0) {
547        strm->state->pending_out = strm->state->pending_buf;
548    }
549}
550
551/* ========================================================================= */
552int ZEXPORT deflate (strm, flush)
553    z_streamp strm;
554    int flush;
555{
556    int old_flush; /* value of flush param for previous deflate call */
557    deflate_state *s;
558
559    if (strm == Z_NULL || strm->state == Z_NULL ||
560        flush > Z_FINISH || flush < 0) {
561        return Z_STREAM_ERROR;
562    }
563    s = strm->state;
564
565    if (strm->next_out == Z_NULL ||
566        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
567        (s->status == FINISH_STATE && flush != Z_FINISH)) {
568        ERR_RETURN(strm, Z_STREAM_ERROR);
569    }
570    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
571
572    s->strm = strm; /* just in case */
573    old_flush = s->last_flush;
574    s->last_flush = flush;
575
576    /* Write the header */
577    if (s->status == INIT_STATE) {
578#ifdef GZIP
579        if (s->wrap == 2) {
580            strm->adler = crc32(0L, Z_NULL, 0);
581            put_byte(s, 31);
582            put_byte(s, 139);
583            put_byte(s, 8);
584            if (s->gzhead == NULL) {
585                put_byte(s, 0);
586                put_byte(s, 0);
587                put_byte(s, 0);
588                put_byte(s, 0);
589                put_byte(s, 0);
590                put_byte(s, s->level == 9 ? 2 :
591                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
592                             4 : 0));
593                put_byte(s, OS_CODE);
594                s->status = BUSY_STATE;
595            }
596            else {
597                put_byte(s, (s->gzhead->text ? 1 : 0) +
598                            (s->gzhead->hcrc ? 2 : 0) +
599                            (s->gzhead->extra == Z_NULL ? 0 : 4) +
600                            (s->gzhead->name == Z_NULL ? 0 : 8) +
601                            (s->gzhead->comment == Z_NULL ? 0 : 16)
602                        );
603                put_byte(s, (Byte)(s->gzhead->time & 0xff));
604                put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
605                put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
606                put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
607                put_byte(s, s->level == 9 ? 2 :
608                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
609                             4 : 0));
610                put_byte(s, s->gzhead->os & 0xff);
611                if (s->gzhead->extra != NULL) {
612                    put_byte(s, s->gzhead->extra_len & 0xff);
613                    put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
614                }
615                if (s->gzhead->hcrc)
616                    strm->adler = crc32(strm->adler, s->pending_buf,
617                                        s->pending);
618                s->gzindex = 0;
619                s->status = EXTRA_STATE;
620            }
621        }
622        else
623#endif
624        {
625            uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
626            uInt level_flags;
627
628            if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
629                level_flags = 0;
630            else if (s->level < 6)
631                level_flags = 1;
632            else if (s->level == 6)
633                level_flags = 2;
634            else
635                level_flags = 3;
636            header |= (level_flags << 6);
637            if (s->strstart != 0) header |= PRESET_DICT;
638            header += 31 - (header % 31);
639
640            s->status = BUSY_STATE;
641            putShortMSB(s, header);
642
643            /* Save the adler32 of the preset dictionary: */
644            if (s->strstart != 0) {
645                putShortMSB(s, (uInt)(strm->adler >> 16));
646                putShortMSB(s, (uInt)(strm->adler & 0xffff));
647            }
648            strm->adler = adler32(0L, Z_NULL, 0);
649        }
650    }
651#ifdef GZIP
652    if (s->status == EXTRA_STATE) {
653        if (s->gzhead->extra != NULL) {
654            uInt beg = s->pending;  /* start of bytes to update crc */
655
656            while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
657                if (s->pending == s->pending_buf_size) {
658                    if (s->gzhead->hcrc && s->pending > beg)
659                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
660                                            s->pending - beg);
661                    flush_pending(strm);
662                    beg = s->pending;
663                    if (s->pending == s->pending_buf_size)
664                        break;
665                }
666                put_byte(s, s->gzhead->extra[s->gzindex]);
667                s->gzindex++;
668            }
669            if (s->gzhead->hcrc && s->pending > beg)
670                strm->adler = crc32(strm->adler, s->pending_buf + beg,
671                                    s->pending - beg);
672            if (s->gzindex == s->gzhead->extra_len) {
673                s->gzindex = 0;
674                s->status = NAME_STATE;
675            }
676        }
677        else
678            s->status = NAME_STATE;
679    }
680    if (s->status == NAME_STATE) {
681        if (s->gzhead->name != NULL) {
682            uInt beg = s->pending;  /* start of bytes to update crc */
683            int val;
684
685            do {
686                if (s->pending == s->pending_buf_size) {
687                    if (s->gzhead->hcrc && s->pending > beg)
688                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
689                                            s->pending - beg);
690                    flush_pending(strm);
691                    beg = s->pending;
692                    if (s->pending == s->pending_buf_size) {
693                        val = 1;
694                        break;
695                    }
696                }
697                val = s->gzhead->name[s->gzindex++];
698                put_byte(s, val);
699            } while (val != 0);
700            if (s->gzhead->hcrc && s->pending > beg)
701                strm->adler = crc32(strm->adler, s->pending_buf + beg,
702                                    s->pending - beg);
703            if (val == 0) {
704                s->gzindex = 0;
705                s->status = COMMENT_STATE;
706            }
707        }
708        else
709            s->status = COMMENT_STATE;
710    }
711    if (s->status == COMMENT_STATE) {
712        if (s->gzhead->comment != NULL) {
713            uInt beg = s->pending;  /* start of bytes to update crc */
714            int val;
715
716            do {
717                if (s->pending == s->pending_buf_size) {
718                    if (s->gzhead->hcrc && s->pending > beg)
719                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
720                                            s->pending - beg);
721                    flush_pending(strm);
722                    beg = s->pending;
723                    if (s->pending == s->pending_buf_size) {
724                        val = 1;
725                        break;
726                    }
727                }
728                val = s->gzhead->comment[s->gzindex++];
729                put_byte(s, val);
730            } while (val != 0);
731            if (s->gzhead->hcrc && s->pending > beg)
732                strm->adler = crc32(strm->adler, s->pending_buf + beg,
733                                    s->pending - beg);
734            if (val == 0)
735                s->status = HCRC_STATE;
736        }
737        else
738            s->status = HCRC_STATE;
739    }
740    if (s->status == HCRC_STATE) {
741        if (s->gzhead->hcrc) {
742            if (s->pending + 2 > s->pending_buf_size)
743                flush_pending(strm);
744            if (s->pending + 2 <= s->pending_buf_size) {
745                put_byte(s, (Byte)(strm->adler & 0xff));
746                put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
747                strm->adler = crc32(0L, Z_NULL, 0);
748                s->status = BUSY_STATE;
749            }
750        }
751        else
752            s->status = BUSY_STATE;
753    }
754#endif
755
756    /* Flush as much pending output as possible */
757    if (s->pending != 0) {
758        flush_pending(strm);
759        if (strm->avail_out == 0) {
760            /* Since avail_out is 0, deflate will be called again with
761             * more output space, but possibly with both pending and
762             * avail_in equal to zero. There won't be anything to do,
763             * but this is not an error situation so make sure we
764             * return OK instead of BUF_ERROR at next call of deflate:
765             */
766            s->last_flush = -1;
767            return Z_OK;
768        }
769
770    /* Make sure there is something to do and avoid duplicate consecutive
771     * flushes. For repeated and useless calls with Z_FINISH, we keep
772     * returning Z_STREAM_END instead of Z_BUF_ERROR.
773     */
774    } else if (strm->avail_in == 0 && flush <= old_flush &&
775               flush != Z_FINISH) {
776        ERR_RETURN(strm, Z_BUF_ERROR);
777    }
778
779    /* User must not provide more input after the first FINISH: */
780    if (s->status == FINISH_STATE && strm->avail_in != 0) {
781        ERR_RETURN(strm, Z_BUF_ERROR);
782    }
783
784    /* Start a new block or continue the current one.
785     */
786    if (strm->avail_in != 0 || s->lookahead != 0 ||
787        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
788        block_state bstate;
789
790        bstate = (*(configuration_table[s->level].func))(s, flush);
791
792        if (bstate == finish_started || bstate == finish_done) {
793            s->status = FINISH_STATE;
794        }
795        if (bstate == need_more || bstate == finish_started) {
796            if (strm->avail_out == 0) {
797                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
798            }
799            return Z_OK;
800            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
801             * of deflate should use the same flush parameter to make sure
802             * that the flush is complete. So we don't have to output an
803             * empty block here, this will be done at next call. This also
804             * ensures that for a very small output buffer, we emit at most
805             * one empty block.
806             */
807        }
808        if (bstate == block_done) {
809            if (flush == Z_PARTIAL_FLUSH) {
810                _tr_align(s);
811            } else { /* FULL_FLUSH or SYNC_FLUSH */
812                _tr_stored_block(s, (char*)0, 0L, 0);
813                /* For a full flush, this empty block will be recognized
814                 * as a special marker by inflate_sync().
815                 */
816                if (flush == Z_FULL_FLUSH) {
817                    CLEAR_HASH(s);             /* forget history */
818                }
819            }
820            flush_pending(strm);
821            if (strm->avail_out == 0) {
822              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
823              return Z_OK;
824            }
825        }
826    }
827    Assert(strm->avail_out > 0, "bug2");
828
829    if (flush != Z_FINISH) return Z_OK;
830    if (s->wrap <= 0) return Z_STREAM_END;
831
832    /* Write the trailer */
833#ifdef GZIP
834    if (s->wrap == 2) {
835        put_byte(s, (Byte)(strm->adler & 0xff));
836        put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
837        put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
838        put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
839        put_byte(s, (Byte)(strm->total_in & 0xff));
840        put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
841        put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
842        put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
843    }
844    else
845#endif
846    {
847        putShortMSB(s, (uInt)(strm->adler >> 16));
848        putShortMSB(s, (uInt)(strm->adler & 0xffff));
849    }
850    flush_pending(strm);
851    /* If avail_out is zero, the application will call deflate again
852     * to flush the rest.
853     */
854    if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
855    return s->pending != 0 ? Z_OK : Z_STREAM_END;
856}
857
858/* ========================================================================= */
859int ZEXPORT deflateEnd (strm)
860    z_streamp strm;
861{
862    int status;
863
864    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
865
866    status = strm->state->status;
867    if (status != INIT_STATE &&
868        status != EXTRA_STATE &&
869        status != NAME_STATE &&
870        status != COMMENT_STATE &&
871        status != HCRC_STATE &&
872        status != BUSY_STATE &&
873        status != FINISH_STATE) {
874      return Z_STREAM_ERROR;
875    }
876
877    /* Deallocate in reverse order of allocations: */
878    TRY_FREE(strm, strm->state->pending_buf);
879    TRY_FREE(strm, strm->state->head);
880    TRY_FREE(strm, strm->state->prev);
881    TRY_FREE(strm, strm->state->window);
882
883    ZFREE(strm, strm->state);
884    strm->state = Z_NULL;
885
886    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
887}
888
889/* =========================================================================
890 * Copy the source state to the destination state.
891 * To simplify the source, this is not supported for 16-bit MSDOS (which
892 * doesn't have enough memory anyway to duplicate compression states).
893 */
894int ZEXPORT deflateCopy (dest, source)
895    z_streamp dest;
896    z_streamp source;
897{
898#ifdef MAXSEG_64K
899    return Z_STREAM_ERROR;
900#else
901    deflate_state *ds;
902    deflate_state *ss;
903    ushf *overlay;
904
905
906    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
907        return Z_STREAM_ERROR;
908    }
909
910    ss = source->state;
911
912    zmemcpy(dest, source, sizeof(z_stream));
913
914    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
915    if (ds == Z_NULL) return Z_MEM_ERROR;
916    dest->state = (struct internal_state FAR *) ds;
917    zmemcpy(ds, ss, sizeof(deflate_state));
918    ds->strm = dest;
919
920    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
921    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
922    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
923    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
924    ds->pending_buf = (uchf *) overlay;
925
926    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
927        ds->pending_buf == Z_NULL) {
928        deflateEnd (dest);
929        return Z_MEM_ERROR;
930    }
931    /* following zmemcpy do not work for 16-bit MSDOS */
932    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
933    zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
934    zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
935    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
936
937    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
938    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
939    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
940
941    ds->l_desc.dyn_tree = ds->dyn_ltree;
942    ds->d_desc.dyn_tree = ds->dyn_dtree;
943    ds->bl_desc.dyn_tree = ds->bl_tree;
944
945    return Z_OK;
946#endif /* MAXSEG_64K */
947}
948
949/* ===========================================================================
950 * Read a new buffer from the current input stream, update the adler32
951 * and total number of bytes read.  All deflate() input goes through
952 * this function so some applications may wish to modify it to avoid
953 * allocating a large strm->next_in buffer and copying from it.
954 * (See also flush_pending()).
955 */
956local int read_buf(strm, buf, size)
957    z_streamp strm;
958    Bytef *buf;
959    unsigned size;
960{
961    unsigned len = strm->avail_in;
962
963    if (len > size) len = size;
964    if (len == 0) return 0;
965
966    strm->avail_in  -= len;
967
968    if (strm->state->wrap == 1) {
969        strm->adler = adler32(strm->adler, strm->next_in, len);
970    }
971#ifdef GZIP
972    else if (strm->state->wrap == 2) {
973        strm->adler = crc32(strm->adler, strm->next_in, len);
974    }
975#endif
976    zmemcpy(buf, strm->next_in, len);
977    strm->next_in  += len;
978    strm->total_in += len;
979
980    return (int)len;
981}
982
983/* ===========================================================================
984 * Initialize the "longest match" routines for a new zlib stream
985 */
986local void lm_init (s)
987    deflate_state *s;
988{
989    s->window_size = (ulg)2L*s->w_size;
990
991    CLEAR_HASH(s);
992
993    /* Set the default configuration parameters:
994     */
995    s->max_lazy_match   = configuration_table[s->level].max_lazy;
996    s->good_match       = configuration_table[s->level].good_length;
997    s->nice_match       = configuration_table[s->level].nice_length;
998    s->max_chain_length = configuration_table[s->level].max_chain;
999
1000    s->strstart = 0;
1001    s->block_start = 0L;
1002    s->lookahead = 0;
1003    s->match_length = s->prev_length = MIN_MATCH-1;
1004    s->match_available = 0;
1005    s->ins_h = 0;
1006#ifndef FASTEST
1007#ifdef ASMV
1008    match_init(); /* initialize the asm code */
1009#endif
1010#endif
1011}
1012
1013#ifndef FASTEST
1014/* ===========================================================================
1015 * Set match_start to the longest match starting at the given string and
1016 * return its length. Matches shorter or equal to prev_length are discarded,
1017 * in which case the result is equal to prev_length and match_start is
1018 * garbage.
1019 * IN assertions: cur_match is the head of the hash chain for the current
1020 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1021 * OUT assertion: the match length is not greater than s->lookahead.
1022 */
1023#ifndef ASMV
1024/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1025 * match.S. The code will be functionally equivalent.
1026 */
1027local uInt longest_match(s, cur_match)
1028    deflate_state *s;
1029    IPos cur_match;                             /* current match */
1030{
1031    unsigned chain_length = s->max_chain_length;/* max hash chain length */
1032    register Bytef *scan = s->window + s->strstart; /* current string */
1033    register Bytef *match;                       /* matched string */
1034    register int len;                           /* length of current match */
1035    int best_len = s->prev_length;              /* best match length so far */
1036    int nice_match = s->nice_match;             /* stop if match long enough */
1037    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1038        s->strstart - (IPos)MAX_DIST(s) : NIL;
1039    /* Stop when cur_match becomes <= limit. To simplify the code,
1040     * we prevent matches with the string of window index 0.
1041     */
1042    Posf *prev = s->prev;
1043    uInt wmask = s->w_mask;
1044
1045#ifdef UNALIGNED_OK
1046    /* Compare two bytes at a time. Note: this is not always beneficial.
1047     * Try with and without -DUNALIGNED_OK to check.
1048     */
1049    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1050    register ush scan_start = *(ushf*)scan;
1051    register ush scan_end   = *(ushf*)(scan+best_len-1);
1052#else
1053    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1054    register Byte scan_end1  = scan[best_len-1];
1055    register Byte scan_end   = scan[best_len];
1056#endif
1057
1058    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1059     * It is easy to get rid of this optimization if necessary.
1060     */
1061    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1062
1063    /* Do not waste too much time if we already have a good match: */
1064    if (s->prev_length >= s->good_match) {
1065        chain_length >>= 2;
1066    }
1067    /* Do not look for matches beyond the end of the input. This is necessary
1068     * to make deflate deterministic.
1069     */
1070    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1071
1072    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1073
1074    do {
1075        Assert(cur_match < s->strstart, "no future");
1076        match = s->window + cur_match;
1077
1078        /* Skip to next match if the match length cannot increase
1079         * or if the match length is less than 2.  Note that the checks below
1080         * for insufficient lookahead only occur occasionally for performance
1081         * reasons.  Therefore uninitialized memory will be accessed, and
1082         * conditional jumps will be made that depend on those values.
1083         * However the length of the match is limited to the lookahead, so
1084         * the output of deflate is not affected by the uninitialized values.
1085         */
1086#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1087        /* This code assumes sizeof(unsigned short) == 2. Do not use
1088         * UNALIGNED_OK if your compiler uses a different size.
1089         */
1090        if (*(ushf*)(match+best_len-1) != scan_end ||
1091            *(ushf*)match != scan_start) continue;
1092
1093        /* It is not necessary to compare scan[2] and match[2] since they are
1094         * always equal when the other bytes match, given that the hash keys
1095         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1096         * strstart+3, +5, ... up to strstart+257. We check for insufficient
1097         * lookahead only every 4th comparison; the 128th check will be made
1098         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1099         * necessary to put more guard bytes at the end of the window, or
1100         * to check more often for insufficient lookahead.
1101         */
1102        Assert(scan[2] == match[2], "scan[2]?");
1103        scan++, match++;
1104        do {
1105        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1106                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1107                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1108                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1109                 scan < strend);
1110        /* The funny "do {}" generates better code on most compilers */
1111
1112        /* Here, scan <= window+strstart+257 */
1113        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1114        if (*scan == *match) scan++;
1115
1116        len = (MAX_MATCH - 1) - (int)(strend-scan);
1117        scan = strend - (MAX_MATCH-1);
1118
1119#else /* UNALIGNED_OK */
1120
1121        if (match[best_len]   != scan_end  ||
1122            match[best_len-1] != scan_end1 ||
1123            *match            != *scan     ||
1124            *++match          != scan[1])      continue;
1125
1126        /* The check at best_len-1 can be removed because it will be made
1127         * again later. (This heuristic is not always a win.)
1128         * It is not necessary to compare scan[2] and match[2] since they
1129         * are always equal when the other bytes match, given that
1130         * the hash keys are equal and that HASH_BITS >= 8.
1131         */
1132        scan += 2, match++;
1133        Assert(*scan == *match, "match[2]?");
1134
1135        /* We check for insufficient lookahead only every 8th comparison;
1136         * the 256th check will be made at strstart+258.
1137         */
1138        do {
1139        } while (*++scan == *++match && *++scan == *++match &&
1140                 *++scan == *++match && *++scan == *++match &&
1141                 *++scan == *++match && *++scan == *++match &&
1142                 *++scan == *++match && *++scan == *++match &&
1143                 scan < strend);
1144
1145        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1146
1147        len = MAX_MATCH - (int)(strend - scan);
1148        scan = strend - MAX_MATCH;
1149
1150#endif /* UNALIGNED_OK */
1151
1152        if (len > best_len) {
1153            s->match_start = cur_match;
1154            best_len = len;
1155            if (len >= nice_match) break;
1156#ifdef UNALIGNED_OK
1157            scan_end = *(ushf*)(scan+best_len-1);
1158#else
1159            scan_end1  = scan[best_len-1];
1160            scan_end   = scan[best_len];
1161#endif
1162        }
1163    } while ((cur_match = prev[cur_match & wmask]) > limit
1164             && --chain_length != 0);
1165
1166    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1167    return s->lookahead;
1168}
1169#endif /* ASMV */
1170#endif /* FASTEST */
1171
1172/* ---------------------------------------------------------------------------
1173 * Optimized version for level == 1 or strategy == Z_RLE only
1174 */
1175local uInt longest_match_fast(s, cur_match)
1176    deflate_state *s;
1177    IPos cur_match;                             /* current match */
1178{
1179    register Bytef *scan = s->window + s->strstart; /* current string */
1180    register Bytef *match;                       /* matched string */
1181    register int len;                           /* length of current match */
1182    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1183
1184    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1185     * It is easy to get rid of this optimization if necessary.
1186     */
1187    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1188
1189    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1190
1191    Assert(cur_match < s->strstart, "no future");
1192
1193    match = s->window + cur_match;
1194
1195    /* Return failure if the match length is less than 2:
1196     */
1197    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1198
1199    /* The check at best_len-1 can be removed because it will be made
1200     * again later. (This heuristic is not always a win.)
1201     * It is not necessary to compare scan[2] and match[2] since they
1202     * are always equal when the other bytes match, given that
1203     * the hash keys are equal and that HASH_BITS >= 8.
1204     */
1205    scan += 2, match += 2;
1206    Assert(*scan == *match, "match[2]?");
1207
1208    /* We check for insufficient lookahead only every 8th comparison;
1209     * the 256th check will be made at strstart+258.
1210     */
1211    do {
1212    } while (*++scan == *++match && *++scan == *++match &&
1213             *++scan == *++match && *++scan == *++match &&
1214             *++scan == *++match && *++scan == *++match &&
1215             *++scan == *++match && *++scan == *++match &&
1216             scan < strend);
1217
1218    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1219
1220    len = MAX_MATCH - (int)(strend - scan);
1221
1222    if (len < MIN_MATCH) return MIN_MATCH - 1;
1223
1224    s->match_start = cur_match;
1225    return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1226}
1227
1228#ifdef DEBUG
1229/* ===========================================================================
1230 * Check that the match at match_start is indeed a match.
1231 */
1232local void check_match(s, start, match, length)
1233    deflate_state *s;
1234    IPos start, match;
1235    int length;
1236{
1237    /* check that the match is indeed a match */
1238    if (zmemcmp(s->window + match,
1239                s->window + start, length) != EQUAL) {
1240        fprintf(stderr, " start %u, match %u, length %d\n",
1241                start, match, length);
1242        do {
1243            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1244        } while (--length != 0);
1245        z_error("invalid match");
1246    }
1247    if (z_verbose > 1) {
1248        fprintf(stderr,"\\[%d,%d]", start-match, length);
1249        do { putc(s->window[start++], stderr); } while (--length != 0);
1250    }
1251}
1252#else
1253#  define check_match(s, start, match, length)
1254#endif /* DEBUG */
1255
1256/* ===========================================================================
1257 * Fill the window when the lookahead becomes insufficient.
1258 * Updates strstart and lookahead.
1259 *
1260 * IN assertion: lookahead < MIN_LOOKAHEAD
1261 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1262 *    At least one byte has been read, or avail_in == 0; reads are
1263 *    performed for at least two bytes (required for the zip translate_eol
1264 *    option -- not supported here).
1265 */
1266local void fill_window(s)
1267    deflate_state *s;
1268{
1269    register unsigned n, m;
1270    register Posf *p;
1271    unsigned more;    /* Amount of free space at the end of the window. */
1272    uInt wsize = s->w_size;
1273
1274    do {
1275        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1276
1277        /* Deal with !@#$% 64K limit: */
1278        if (sizeof(int) <= 2) {
1279            if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1280                more = wsize;
1281
1282            } else if (more == (unsigned)(-1)) {
1283                /* Very unlikely, but possible on 16 bit machine if
1284                 * strstart == 0 && lookahead == 1 (input done a byte at time)
1285                 */
1286                more--;
1287            }
1288        }
1289
1290        /* If the window is almost full and there is insufficient lookahead,
1291         * move the upper half to the lower one to make room in the upper half.
1292         */
1293        if (s->strstart >= wsize+MAX_DIST(s)) {
1294
1295            zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1296            s->match_start -= wsize;
1297            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
1298            s->block_start -= (long) wsize;
1299
1300            /* Slide the hash table (could be avoided with 32 bit values
1301               at the expense of memory usage). We slide even when level == 0
1302               to keep the hash table consistent if we switch back to level > 0
1303               later. (Using level 0 permanently is not an optimal usage of
1304               zlib, so we don't care about this pathological case.)
1305             */
1306            /* %%% avoid this when Z_RLE */
1307            n = s->hash_size;
1308            p = &s->head[n];
1309            do {
1310                m = *--p;
1311                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1312            } while (--n);
1313
1314            n = wsize;
1315#ifndef FASTEST
1316            p = &s->prev[n];
1317            do {
1318                m = *--p;
1319                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1320                /* If n is not on any hash chain, prev[n] is garbage but
1321                 * its value will never be used.
1322                 */
1323            } while (--n);
1324#endif
1325            more += wsize;
1326        }
1327        if (s->strm->avail_in == 0) return;
1328
1329        /* If there was no sliding:
1330         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1331         *    more == window_size - lookahead - strstart
1332         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1333         * => more >= window_size - 2*WSIZE + 2
1334         * In the BIG_MEM or MMAP case (not yet supported),
1335         *   window_size == input_size + MIN_LOOKAHEAD  &&
1336         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1337         * Otherwise, window_size == 2*WSIZE so more >= 2.
1338         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1339         */
1340        Assert(more >= 2, "more < 2");
1341
1342        n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1343        s->lookahead += n;
1344
1345        /* Initialize the hash value now that we have some input: */
1346        if (s->lookahead >= MIN_MATCH) {
1347            s->ins_h = s->window[s->strstart];
1348            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1349#if MIN_MATCH != 3
1350            Call UPDATE_HASH() MIN_MATCH-3 more times
1351#endif
1352        }
1353        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1354         * but this is not important since only literal bytes will be emitted.
1355         */
1356
1357    } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1358}
1359
1360/* ===========================================================================
1361 * Flush the current block, with given end-of-file flag.
1362 * IN assertion: strstart is set to the end of the current match.
1363 */
1364#define FLUSH_BLOCK_ONLY(s, eof) { \
1365   _tr_flush_block(s, (s->block_start >= 0L ? \
1366                   (charf *)&s->window[(unsigned)s->block_start] : \
1367                   (charf *)Z_NULL), \
1368                (ulg)((long)s->strstart - s->block_start), \
1369                (eof)); \
1370   s->block_start = s->strstart; \
1371   flush_pending(s->strm); \
1372   Tracev((stderr,"[FLUSH]")); \
1373}
1374
1375/* Same but force premature exit if necessary. */
1376#define FLUSH_BLOCK(s, eof) { \
1377   FLUSH_BLOCK_ONLY(s, eof); \
1378   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1379}
1380
1381/* ===========================================================================
1382 * Copy without compression as much as possible from the input stream, return
1383 * the current block state.
1384 * This function does not insert new strings in the dictionary since
1385 * uncompressible data is probably not useful. This function is used
1386 * only for the level=0 compression option.
1387 * NOTE: this function should be optimized to avoid extra copying from
1388 * window to pending_buf.
1389 */
1390local block_state deflate_stored(s, flush)
1391    deflate_state *s;
1392    int flush;
1393{
1394    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1395     * to pending_buf_size, and each stored block has a 5 byte header:
1396     */
1397    ulg max_block_size = 0xffff;
1398    ulg max_start;
1399
1400    if (max_block_size > s->pending_buf_size - 5) {
1401        max_block_size = s->pending_buf_size - 5;
1402    }
1403
1404    /* Copy as much as possible from input to output: */
1405    for (;;) {
1406        /* Fill the window as much as possible: */
1407        if (s->lookahead <= 1) {
1408
1409            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1410                   s->block_start >= (long)s->w_size, "slide too late");
1411
1412            fill_window(s);
1413            if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1414
1415            if (s->lookahead == 0) break; /* flush the current block */
1416        }
1417        Assert(s->block_start >= 0L, "block gone");
1418
1419        s->strstart += s->lookahead;
1420        s->lookahead = 0;
1421
1422        /* Emit a stored block if pending_buf will be full: */
1423        max_start = s->block_start + max_block_size;
1424        if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1425            /* strstart == 0 is possible when wraparound on 16-bit machine */
1426            s->lookahead = (uInt)(s->strstart - max_start);
1427            s->strstart = (uInt)max_start;
1428            FLUSH_BLOCK(s, 0);
1429        }
1430        /* Flush if we may have to slide, otherwise block_start may become
1431         * negative and the data will be gone:
1432         */
1433        if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1434            FLUSH_BLOCK(s, 0);
1435        }
1436    }
1437    FLUSH_BLOCK(s, flush == Z_FINISH);
1438    return flush == Z_FINISH ? finish_done : block_done;
1439}
1440
1441/* ===========================================================================
1442 * Compress as much as possible from the input stream, return the current
1443 * block state.
1444 * This function does not perform lazy evaluation of matches and inserts
1445 * new strings in the dictionary only for unmatched strings or for short
1446 * matches. It is used only for the fast compression options.
1447 */
1448local block_state deflate_fast(s, flush)
1449    deflate_state *s;
1450    int flush;
1451{
1452    IPos hash_head = NIL; /* head of the hash chain */
1453    int bflush;           /* set if current block must be flushed */
1454
1455    for (;;) {
1456        /* Make sure that we always have enough lookahead, except
1457         * at the end of the input file. We need MAX_MATCH bytes
1458         * for the next match, plus MIN_MATCH bytes to insert the
1459         * string following the next match.
1460         */
1461        if (s->lookahead < MIN_LOOKAHEAD) {
1462            fill_window(s);
1463            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1464                return need_more;
1465            }
1466            if (s->lookahead == 0) break; /* flush the current block */
1467        }
1468
1469        /* Insert the string window[strstart .. strstart+2] in the
1470         * dictionary, and set hash_head to the head of the hash chain:
1471         */
1472        if (s->lookahead >= MIN_MATCH) {
1473            INSERT_STRING(s, s->strstart, hash_head);
1474        }
1475
1476        /* Find the longest match, discarding those <= prev_length.
1477         * At this point we have always match_length < MIN_MATCH
1478         */
1479        if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1480            /* To simplify the code, we prevent matches with the string
1481             * of window index 0 (in particular we have to avoid a match
1482             * of the string with itself at the start of the input file).
1483             */
1484#ifdef FASTEST
1485            if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1486                (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1487                s->match_length = longest_match_fast (s, hash_head);
1488            }
1489#else
1490            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1491                s->match_length = longest_match (s, hash_head);
1492            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1493                s->match_length = longest_match_fast (s, hash_head);
1494            }
1495#endif
1496            /* longest_match() or longest_match_fast() sets match_start */
1497        }
1498        if (s->match_length >= MIN_MATCH) {
1499            check_match(s, s->strstart, s->match_start, s->match_length);
1500
1501            _tr_tally_dist(s, s->strstart - s->match_start,
1502                           s->match_length - MIN_MATCH, bflush);
1503
1504            s->lookahead -= s->match_length;
1505
1506            /* Insert new strings in the hash table only if the match length
1507             * is not too large. This saves time but degrades compression.
1508             */
1509#ifndef FASTEST
1510            if (s->match_length <= s->max_insert_length &&
1511                s->lookahead >= MIN_MATCH) {
1512                s->match_length--; /* string at strstart already in table */
1513                do {
1514                    s->strstart++;
1515                    INSERT_STRING(s, s->strstart, hash_head);
1516                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1517                     * always MIN_MATCH bytes ahead.
1518                     */
1519                } while (--s->match_length != 0);
1520                s->strstart++;
1521            } else
1522#endif
1523            {
1524                s->strstart += s->match_length;
1525                s->match_length = 0;
1526                s->ins_h = s->window[s->strstart];
1527                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1528#if MIN_MATCH != 3
1529                Call UPDATE_HASH() MIN_MATCH-3 more times
1530#endif
1531                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1532                 * matter since it will be recomputed at next deflate call.
1533                 */
1534            }
1535        } else {
1536            /* No match, output a literal byte */
1537            Tracevv((stderr,"%c", s->window[s->strstart]));
1538            _tr_tally_lit (s, s->window[s->strstart], bflush);
1539            s->lookahead--;
1540            s->strstart++;
1541        }
1542        if (bflush) FLUSH_BLOCK(s, 0);
1543    }
1544    FLUSH_BLOCK(s, flush == Z_FINISH);
1545    return flush == Z_FINISH ? finish_done : block_done;
1546}
1547
1548#ifndef FASTEST
1549/* ===========================================================================
1550 * Same as above, but achieves better compression. We use a lazy
1551 * evaluation for matches: a match is finally adopted only if there is
1552 * no better match at the next window position.
1553 */
1554local block_state deflate_slow(s, flush)
1555    deflate_state *s;
1556    int flush;
1557{
1558    IPos hash_head = NIL;    /* head of hash chain */
1559    int bflush;              /* set if current block must be flushed */
1560
1561    /* Process the input block. */
1562    for (;;) {
1563        /* Make sure that we always have enough lookahead, except
1564         * at the end of the input file. We need MAX_MATCH bytes
1565         * for the next match, plus MIN_MATCH bytes to insert the
1566         * string following the next match.
1567         */
1568        if (s->lookahead < MIN_LOOKAHEAD) {
1569            fill_window(s);
1570            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1571                return need_more;
1572            }
1573            if (s->lookahead == 0) break; /* flush the current block */
1574        }
1575
1576        /* Insert the string window[strstart .. strstart+2] in the
1577         * dictionary, and set hash_head to the head of the hash chain:
1578         */
1579        if (s->lookahead >= MIN_MATCH) {
1580            INSERT_STRING(s, s->strstart, hash_head);
1581        }
1582
1583        /* Find the longest match, discarding those <= prev_length.
1584         */
1585        s->prev_length = s->match_length, s->prev_match = s->match_start;
1586        s->match_length = MIN_MATCH-1;
1587
1588        if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1589            s->strstart - hash_head <= MAX_DIST(s)) {
1590            /* To simplify the code, we prevent matches with the string
1591             * of window index 0 (in particular we have to avoid a match
1592             * of the string with itself at the start of the input file).
1593             */
1594            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1595                s->match_length = longest_match (s, hash_head);
1596            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1597                s->match_length = longest_match_fast (s, hash_head);
1598            }
1599            /* longest_match() or longest_match_fast() sets match_start */
1600
1601            if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1602#if TOO_FAR <= 32767
1603                || (s->match_length == MIN_MATCH &&
1604                    s->strstart - s->match_start > TOO_FAR)
1605#endif
1606                )) {
1607
1608                /* If prev_match is also MIN_MATCH, match_start is garbage
1609                 * but we will ignore the current match anyway.
1610                 */
1611                s->match_length = MIN_MATCH-1;
1612            }
1613        }
1614        /* If there was a match at the previous step and the current
1615         * match is not better, output the previous match:
1616         */
1617        if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1618            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1619            /* Do not insert strings in hash table beyond this. */
1620
1621            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1622
1623            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1624                           s->prev_length - MIN_MATCH, bflush);
1625
1626            /* Insert in hash table all strings up to the end of the match.
1627             * strstart-1 and strstart are already inserted. If there is not
1628             * enough lookahead, the last two strings are not inserted in
1629             * the hash table.
1630             */
1631            s->lookahead -= s->prev_length-1;
1632            s->prev_length -= 2;
1633            do {
1634                if (++s->strstart <= max_insert) {
1635                    INSERT_STRING(s, s->strstart, hash_head);
1636                }
1637            } while (--s->prev_length != 0);
1638            s->match_available = 0;
1639            s->match_length = MIN_MATCH-1;
1640            s->strstart++;
1641
1642            if (bflush) FLUSH_BLOCK(s, 0);
1643
1644        } else if (s->match_available) {
1645            /* If there was no match at the previous position, output a
1646             * single literal. If there was a match but the current match
1647             * is longer, truncate the previous match to a single literal.
1648             */
1649            Tracevv((stderr,"%c", s->window[s->strstart-1]));
1650            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1651            if (bflush) {
1652                FLUSH_BLOCK_ONLY(s, 0);
1653            }
1654            s->strstart++;
1655            s->lookahead--;
1656            if (s->strm->avail_out == 0) return need_more;
1657        } else {
1658            /* There is no previous match to compare with, wait for
1659             * the next step to decide.
1660             */
1661            s->match_available = 1;
1662            s->strstart++;
1663            s->lookahead--;
1664        }
1665    }
1666    Assert (flush != Z_NO_FLUSH, "no flush?");
1667    if (s->match_available) {
1668        Tracevv((stderr,"%c", s->window[s->strstart-1]));
1669        _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1670        s->match_available = 0;
1671    }
1672    FLUSH_BLOCK(s, flush == Z_FINISH);
1673    return flush == Z_FINISH ? finish_done : block_done;
1674}
1675#endif /* FASTEST */
1676
1677#if 0
1678/* ===========================================================================
1679 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1680 * one.  Do not maintain a hash table.  (It will be regenerated if this run of
1681 * deflate switches away from Z_RLE.)
1682 */
1683local block_state deflate_rle(s, flush)
1684    deflate_state *s;
1685    int flush;
1686{
1687    int bflush;         /* set if current block must be flushed */
1688    uInt run;           /* length of run */
1689    uInt max;           /* maximum length of run */
1690    uInt prev;          /* byte at distance one to match */
1691    Bytef *scan;        /* scan for end of run */
1692
1693    for (;;) {
1694        /* Make sure that we always have enough lookahead, except
1695         * at the end of the input file. We need MAX_MATCH bytes
1696         * for the longest encodable run.
1697         */
1698        if (s->lookahead < MAX_MATCH) {
1699            fill_window(s);
1700            if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1701                return need_more;
1702            }
1703            if (s->lookahead == 0) break; /* flush the current block */
1704        }
1705
1706        /* See how many times the previous byte repeats */
1707        run = 0;
1708        if (s->strstart > 0) {      /* if there is a previous byte, that is */
1709            max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
1710            scan = s->window + s->strstart - 1;
1711            prev = *scan++;
1712            do {
1713                if (*scan++ != prev)
1714                    break;
1715            } while (++run < max);
1716        }
1717
1718        /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1719        if (run >= MIN_MATCH) {
1720            check_match(s, s->strstart, s->strstart - 1, run);
1721            _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
1722            s->lookahead -= run;
1723            s->strstart += run;
1724        } else {
1725            /* No match, output a literal byte */
1726            Tracevv((stderr,"%c", s->window[s->strstart]));
1727            _tr_tally_lit (s, s->window[s->strstart], bflush);
1728            s->lookahead--;
1729            s->strstart++;
1730        }
1731        if (bflush) FLUSH_BLOCK(s, 0);
1732    }
1733    FLUSH_BLOCK(s, flush == Z_FINISH);
1734    return flush == Z_FINISH ? finish_done : block_done;
1735}
1736#endif
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